Device for the accumulation of materials in strips

Abstract

Elongated strip material is accumulated within a limited accumulation space between two parallel vertical plates in multiple turns within and inner and outer cage, the two cages being substantially cylindrical and formed of horizontal rollers mounted for rotation on fixed pivots such that the strip material is accumulated in a single spiral coil comprising at least two turns with the outer spiral and the inner spiral each being in communication to the exterior of that space through pairs of gripping rollers characterized by the taking out of the inner turns achieved by forming a helicoidal floating turn, the two ends of which are nipped between two gripping rollers in side by side fashion.

I claim: 
     
       1. A device for the accumulation of elongated strip material of considerable length, said device comprising: an outer cage, an inner cage, said two cages being substantially cylindrical and comprising sets of horizontal rollers mounted for rotation on fixed pivots disposed substantially between two parallel vertical plates, said cages and said plates defining an accumulation space slightly wider than the width of said strip material in which the strip material is accumulated in a single spiral coil comprising at least two turns and forming outer and inner spirals, multiple pairs of gripper rollers for gripping respective strip material spirals to the inside and outside of said inner and outer sprials, respectively, and wherein the inner turn of the inner spiral is nipped at both its ends between at least one inner pair of said gripper rollers to form a helicoidal floating turn and one of said plates has an opening within the inner cage through which the inner pair of gripper rollers and one end of said helicoidal floating turn protrudes from said accumulation space. 
     
     
       2. The device according to claim 1, wherein the inner pair of gripper rollers have a length at least twice the width of the strip material, so as to simultaneously nip the two ends of the helicoidal floating turn with said ends positioned side by side. 
     
     
       3. The device according to claim 2, the inner pair of gripper rollers comprise means for simultaneously nipping the two ends of the helical turn and driving said two ends at the same velocity. 
     
     
       4. The device according to claim 1, further comprising means for driving the lower rollers of the outer cage at the same velocity as the outer pair of gripper rollers. 
     
     
       5. A process for the accumulation of a limited length of a travelling strip material during its travelling movement and wherein the strip length being accumulated may be different from the length of strip material leaving the area of accumulation, said method being characterised by the steps of forming a sprial of said strip material comprising a plurality of turns the diameters of whch may vary between the maximum diameter for an outer turn and a minimum diameter for the inner turn, commonly gripping both ends of the inner turn of the strip material leaving the spiral to form a helical trace, in such a manner that the axis of the downstream portion of the strip material is laterally offset from the axis of the upstream portion of the strip material relative to the inner turn by a distance greater than the strip width.